Flotation method

Abstract

A method of improving the quality of froth removed from a minerals separation flotation cell by providing converging side walls to crowd the froth into a narrower chimney and thereby increase the froth height. The riser is constructed so that the height of the froth from the pulp/froth interface to the froth overflow weir is greater than the natural froth height in a similar parallel-sided flotation cell.

What I claim is: 
     
       1. A method of improving the yield of a minerals separation froth flotation cell employed in the separation of one mineral from another, the cell being of the type having aerator means in the cell for producing bubbles in the liquid pulp within the cell causing a froth to form on top of the pulp to a natural froth height, the cell further incorporating an overflow lip positioned in the side of the cell at a height between the pulp/froth interface and the top of the froth allowing the froth, bearing entrained minerals, to overlow into a launder for collection, the method comprising the steps of providing a collecting hood having a lower peripheral edge and inwardly converging sides extending upwardly from the edge to a substantially vertical froth collection shaft havig an overflow weir therein, immersing the lower peripheral edge into the cell to a sufficient depth to cause the froth to rise upwardly within the collection shaft and overflow the weir thereby defining a new froth height from the pulp/froth interface to the weir, the collection shaft having a sufficient vertical dimension such that when said lower edge is immersed in said cell to said sufficient depth the new froth height is greater than the natural froth height.   
     
     
       2. A method as claimed in claim 1 wherein the collecting hood is positioned and arranged such that the height of the froth from the pulp/froth interface to the overflow weir is greater than the natural height of the froth multiplied by the horizontal cross-sectional area of the hood at the lower peripheral edge and divided by the horizontal cross-sectional area of the collection shaft at the level of the overflow weir. 
     
     
       3. A method as claimed in claim 1 wherein the walls of the froth collection shaft are substantially parallel and wherein the collecting hood is positioned within the cell to locate the pulp froth interface within the froth collection shaft. 
     
     
       4. A method as claimed in claim 3 wherein the froth height from the pulp/froth interface to the overflow weir is greater than the smallest transverse width of the froth collection shaft. 
     
     
       5. A method as claimed in claim 1 wherein the collecting hood is positioned to locate the pulp/froth interface at or about the base of the froth collection shaft. 
     
     
       6. A method as claimed in claim 1 wherein the collecting hood is positioned to locate the pulp/froth interface between the lower peripheral edge of the hood and the base of the froth collection shaft. 
     
     
       7. A method as claimed in claim 1 wherein the configuration of the collecting hood and the position of the overflow weir is such that the path length of each bubble from the pulp/froth interface to the oveflow weir is substantially the same. 
     
     
       8. A method as claimed in claim 1 wherein the ratio of the horizontal cross-sectional area of the froth collection shaft at the level of the overflow weir to the horizontal cross-sectional area of the collecting hood at the lower peripheral edge is between 99:100 and 1:100. 
     
     
       9. A method as claimed in claim 8 wherein the said ratio is between 99:100 and 1:5.